The present invention is in the field of forming joints between pipes, ducts, and fittings. The present invention is particularly useful in joining ducts together in order to preassemble encapsulating structures for processing equipment used in the manufacture of microelectronic devices, particularly with inert polymer materials, because the resultant joints between the encapsulation member components are accurately aligned, substantially distortion free, strong for long service life, and impermeable to metal ions.
There are many circumstances in which it is desirable to encapsulate a substrate with some kind of protective barrier. In some circumstances, encapsulation can be used to protect the substrate from the environment in which the substrate will be used. For example, encapsulation is useful when the substrate is a metal component or the like that is to be used in a marine environment where salt water or the corresponding vapor or mist can corrode or otherwise damage the unprotected component. Encapsulation can also be used to protect processing equipment to be used in acidic, basic, reducing, or oxidizing environments.
In other circumstances, it may be desirable to protect items in the environment from the substrate itself. For instance, one step of manufacturing microelectronic devices involves processing those devices while the devices are supported upon some kind of structure, such as a wafer cassette, platform, transport apparatus, rotating turntable, and/or the like. For strength, rotating turntables and other structures used to process microelectronic devices are often formed from one or more metals, metal alloys, intermetallic compositions, or the like. Unfortunately, metal ions from such metallic structures can migrate from the structures into the devices being processed. This is especially problematic and may even destroy the functional capability of the devices. To protect microelectronic devices from contamination during processing, the industry has encapsulated one or more components of the processing equipment in an inert polymer, e.g., a fluoropolymer such as perfluoroalkoxy polymer (PFA), a fluoroethylene polymer (FEP), an ethylene tetra fluoroethylene polymer, (ETFE), a polyvinylidene fluoride polymer (PVDF), a polyvinyl fluoride polymer (PVF), combinations of these, and the like.
To encapsulate a particular structure with an inert polymer, one or more encapsulating parts may be pre-formed and then assembled around the structure. The parts may be joined using glue, fusing techniques, or the like. In the microelectronics industry, the encapsulating joints must be strong enough so that the encapsulated structure can withstand the rigors of use over a reasonably long service life. If the substrate comprises metal, the encapsulation joint should be impermeable to metal ions.
Forming encapsulating joints that meet the stringent demands of the microelectronic industry has been extremely challenging. The difficulty is due, at least in part, to the complex geometry of the structures that require encapsulation. For example, the MERCURY(copyright) centrifugal spray processors commercially available from FSI International, Chaska, Minn., each include an encapsulated, rotating turntable that supports several wafer cassettes during processing. This turntable has projecting, upright structures including uprights that help hold the wafer cassettes. It previously has been difficult and time consuming to satisfactorily bond encapsulating structures in position over these uprights. Generally, to form such an encapsulating structure, an encapsulating top cover is positioned over the top of the turntable. The top cover has a number of apertures matched to the upright structures so that the uprights project upward through these apertures when the cover is in place. Encapsulating sleeves are placed over these uprights and then bonded to the top cover. In short, the encapsulating structure is assembled around the turntable.
It would be much more desirable to be able to preassemble the top cover and sleeves and then fit the preassembled structure over the uprights and turntable like a glove. However, there are a number of challenges that would have to be overcome in order for this approach to be feasible. First, the sleeves must be accurately positioned when bonded to the cover. To appreciate this, it is helpful to consider that the pre-assembly of the sleeve and cover generally involves joining the mating faces of a pair of ducts together. The sleeve is a duct closed at one end, but open at the other. The cover itself will include a number of through apertures through which the uprights of the turntable project when the cover is positioned over the turntable. The open end of the tube must be bonded to the cover so that the opening of the tube is accurately positioned over a corresponding opening through the cover. Any misalignment between these ducts may prevent the pre-assembled cover from properly fitting over the turntable.
Additionally, methods for bonding encapsulating components together require that the mating faces of the parts be pressed into contact with each other using some pressure while the joint between the parts fuses. Depending upon whether glue or fusion techniques are being used, a bead of glue or molten material, as the case may be, tends to form around the joint on both the inside and outside of the resultant structure. The formation of such a bead on the interior is particularly problematic because the bead reduces the interior cross-section of the structure. The reduced cross-section can make it difficult, or impossible, to fit the encapsulated structure over the turntable, even if alignment between the bonded parts is accurate.
Third, the cross-sectional shape of each sleeve is generally carefully matched to that of the corresponding upright so that the sleeve fits over the upright with little, if any, play. In some instances, the methods used to press the sleeve into bonding contact with the cover during a conventional preassembly can distort the cross-section of the sleeve. This distortion, too, tends to cause a poor fit over the turntable uprights.
Fourth, the bond must be strong enough to withstand the rigors of the intended use. If the bond fails, the integrity of the encapsulating structure is obviously compromised. Desirably, therefore, the joint between components should be at least as strong as the materials being joined.
Preassembling encapsulating structures is not the only situation in which mating faces of ducts must be accurately bonded together. Indeed, this issue arises in any circumstance in which ducts, whether encapsulating components, pipes, fittings, or the like, are joined together. For example, when joining pipes together to form a fluid transport system, misalignment, bead formation on the interior of joined pipes, a weak joint, and/or distorted cross-sections can impede fluid flow through the assembled pipes. In some instances, larger, more expensive pumps might be required to provide fluid transport due to the additional, undue pressure drop caused by such problems. In other instances in which fluids must be transferred through piping under laminar flow conditions, such problems can cause intolerable turbulence to occur.
There is thus a continuing need for improved processes and structures for accurately joining ducts together, particularly when pre-assembling encapsulating structures or when assembling networks for transporting fluids. An effective and efficient process and apparatus that provides a clean, accurate, nondistorted, durable, impermeable bond between duct components would be highly desirable.
The present invention advantageously provides an approach for accurately joining ducts together such that the joint is clean, accurate, nondistorted, durable, and impermeable to metal ions. The present invention is based, at least in part, upon the concept of using a removable alignment member that can be used to support ducts while the ducts are being joined. The resultant joints are extremely uniform, making the present invention particularly useful in mass production. For example, the present invention can be used to mass produce pre-assembled encapsulating structures subject to relatively tight specifications. The joints between ducts are easy and economical to make using simple equipment. The joints can be made using any kind of joining technique, such as gluing, welding, or the like. Welding is the preferred technique for joining thermoplastic ducts.
In one aspect, the present invention provides a method of joining a mating face of a first through duct to a mating face of a second duct. specifically, the method comprises the steps of:
(a) bonding the first duct mating face to the second duct mating face to form a bonded structure, said bonding occurring while the ducts are supported in alignment with each other on an alignment member; and
(b) after bonding the mating faces of the ducts together, causing the alignment member to be removed from the bonded structure.
In another aspect, the present invention provides a method of encapsulating at least a portion of an article comprising a surface and a plurality of structures projecting from the surface. In particular, the method comprises the steps of:
(a) providing a first encapsulating component comprising a plurality of through ducts, said through ducts corresponding to at least a portion of said projecting structures such that said portion of the projecting structures fit through the through ducts when the first encapsulating component is positioned over the surface of the article;
(b) providing a second encapsulating component comprising a duct corresponding to a through duct of the first encapsulating component, said duct of the second encapsulating component defining at least a portion of an encapsulating chamber for receiving a projecting structure when the duct of the second encapsulating component is bonded to the corresponding duct of the first encapsulating component;
(c) bonding the duct of the second encapsulating component to the corresponding through duct of the first encapsulating component to form a pre-assembled encapsulating structure, said bonding occurring while the ducts are supported in alignment with each other on an alignment member;
(d) after bonding the ducts together, removing the alignment member from the pre-assembled encapsulating structure;
(e) optionally bonding one or more additional encapsulating components to the first encapsulating component; and
(f) fitting the pre-assembled encapsulating structure over the article in a manner such that a projecting structure is received in the encapsulating chamber.
In yet another aspect, the present invention provides a method of joining a plurality of ducts of a plurality of polymeric members to corresponding through ducts of a polymeric body. In this embodiment of the invention, the method comprises the steps of:
(a) rotatably supporting the polymeric body such that at least one through duct is in a bonding position;
(b) bonding a polymeric member to the polymeric body such that the duct of said polymeric member is aligned with the through duct of the polymeric body in the bonding position;
(c) during bonding, causing an alignment member to be positioned inside the ducts to be bonded together such that the joint between the ducts is supported by said alignment member;
(d) after bonding, removing the alignment member from the bonded structure;
(e) rotating the polymeric body to cause at least one successive through duct to be in a bonding position; and
(f) bonding at least one additional polymeric member to the polymeric body.
Finally, in yet another aspect, the present invention provides a method of forming an encapsulating structure, comprising the steps of:
(a) providing a first encapsulating component comprising a first face, a second face, and a through duct extending through the first encapsulating component from the first face to the second face;
(b) providing a second encapsulating component having a duct that extends from and end face of the second encapsulating component along at least a portion of the length of the second encapsulating component;
(c) positioning the end face of the second encapsulating component in a spaced apart and confronting relationship with the second face of the first encapsulating component such that the ducts of the components are aligned;
(d) heating the confronting faces of the first and second encapsulating components under conditions such that the end face and second face are fusibly weldable to each other;
(e) inserting an alignment member into the through duct of the first encapsulating component such that at least a portion of the alignment member extends from the second face of the first encapsulating component in a direction toward the end face of the second encapsulating component;
(f) fusibly contacting the end face and second face at a joint to form the encapsulating structure in which the ducts of the components cooperate to define an encapsulating chamber, said contacting occurring while the joint between the faces is supported by the alignment member; and
(g) removing the alignment member from the encapsulating structure.